[llvm] [LV] Remove selectUserVF, remove use of legacy expectedCost (NFCI) (PR #191216)

[Florian Hahn via llvm-commits]

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@@ -5014,43 +4999,22 @@ InstructionCost LoopVectorizationCostModel::expectedCost(ElementCount VF) {
     // For each instruction in the old loop.
     for (Instruction &I : *BB) {
       // Skip ignored values.
-      if (ValuesToIgnore.count(&I) || ValuesToIgnoreForVF.count(&I) ||
+      if (ValuesToIgnore.count(&I) ||
           (VF.isVector() && VecValuesToIgnore.count(&I)))
         continue;
 
       InstructionCost C = getInstructionCost(&I, VF);
 
       // Check if we should override the cost.
-      if (C.isValid() && ForceTargetInstructionCost.getNumOccurrences() > 0) {
-        // For interleave groups, use ForceTargetInstructionCost once for the
-        // whole group.
-        if (VF.isVector() && getWideningDecision(&I, VF) == CM_Interleave) {
-          if (getInterleavedAccessGroup(&I)->getInsertPos() == &I)
-            C = InstructionCost(ForceTargetInstructionCost);
-          else
-            C = InstructionCost(0);
-        } else {
-          C = InstructionCost(ForceTargetInstructionCost);
-        }
-      }
+      if (C.isValid() && ForceTargetInstructionCost.getNumOccurrences() > 0)
+        C = InstructionCost(ForceTargetInstructionCost);
 
       BlockCost += C;
       LLVM_DEBUG(dbgs() << "LV: Found an estimated cost of " << C << " for VF "
                         << VF << " For instruction: " << I << '\n');
     }
 
-    // If we are vectorizing a predicated block, it will have been
-    // if-converted. This means that the block's instructions (aside from
-    // stores and instructions that may divide by zero) will now be
-    // unconditionally executed. For the scalar case, we may not always execute
-    // the predicated block, if it is an if-else block. Thus, scale the block's
-    // cost by the probability of executing it.
-    // getPredBlockCostDivisor will return 1 for blocks that are only predicated
-    // by the header mask when folding the tail.
-    if (VF.isScalar())
-      BlockCost /= getPredBlockCostDivisor(CostKind, BB);
-
-    Cost += BlockCost;
+    Cost += BlockCost / getPredBlockCostDivisor(CostKind, BB);
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fhahn wrote:

Thanks, I added back a slightly re-worded version regarding the scalar loop

https://github.com/llvm/llvm-project/pull/191216